<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
<style>
    [type]{
        color: blue;
    }
    [type=password]{
        color: red;
    }
</style>
</head>
<body>
用户名：<input type="text" required/> <br/>
密码：<input type="password"/> <br/>
邮箱：<input type="email"/> <br/>
</body>
</html>